Modeling sound fields generated by multi-nodal communications networks found in underwater industrial settings

Abstract

Increasingly as the sea becomes host to marine industrial operations, mid-to-high frequency multi-nodal communication systems are being employed to monitor equipment states and to control remotely controlled and autonomous underwater vessels used to service and tend underwater equipment. From a regulatory standpoint most of this equipment is modeled as single point noise sources and propagation concerns are ameliorated by high-frequency attenuation due to sound absorption through frequency-dependent chemical “relaxation” or “elasticity” characteristics of boric acid (BH3O3) and magnesium sulphate (MgSO4) components in seawater, and assumptions of the directionality of high-frequency signals. But due to the multi-nodal aspect of their operations, these networks actually set up a broad sound field that can be operationally detected at distances in excess of 10km. In this paper we approximate the characteristics of these sound fields by propagation modeling under realistic, but hypothetical scenarios that would be found in offshore and subsea fossil fuel extraction and renewable energy harvesting operations.